An Aerodynamic Shroud for Automotive Cooling Fans

Abstract

Results from an experimental investigation of an aerodynamic fan shroud are reported. The device was motivated by the relatively large (2.5 cm) tip clearance required in automotive cooling fans which are mounted to the engine. The shroud consists of a pressurized plenum and a Coanda attachment surface to deliver a jet of high momentum air into the tip clearance region. Both the performance and the efficiency for the initial system design were enhanced at higher flow rates, and degraded at lower flow rates. A small tuft was used to observe qualitative flow features in the near wake and tip clearance region of the fan. This information was used to create a modified design. The new geometry was tested and found to provide improved performance characteristics for a wider range of flow rate conditions.